Resistance unit



April 14, 1925.

1,533,096- F.YH. BULLINGER RESISTANCE UNIT Ei1ed Aug. 24; 1922 Patented Apr. 14, 1925.

UNITED STATES PATENT oF lcE;

FREDERIG H. BULLINGER, 0F YONKERS, YORK, ASSIGNOE TO WARD LEONARD ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RESISTANCE UNIT.

Application filed August 24, 1922- Serial No. 583,955.

To all whom it may concern:

Be it known that I, FREDERIC H. BULLIN- GER, a citizen of the United States, residing at Yonkers, in the county of Westchester and State of New York, have invented cer-' tain new and useful Improvements in Resistance Units, of which the following is a specification.

This invention relates particularly to resistance units of the tubular type, wherein the resistive wires are wound upon aninsulating tube and covered with an insulating coating, such as vitreous enamel, or other coating, which is fused or baked in a fur: nace at comparatively high temperature. The invention also particularly relates to such a tubular unit wherein it is desired to" have rigid terminal connections on the unit itself and which may in some cases be utilized for supporting the unit from its terminal connections.

These devices are sometimes wound with many turns of small sized wire for giving a high resistance between terminals and sometimes have comparatively large conductors of correspondingly large carrying capacity and are preferably in the form of braided wires. There are also intermediate sizes and forms of conductors. It is likewise common to provide intermediate terminals, or taps, and in some instancesbetween certain terminals the wire willbe small and between others on the same unit the resistive conductor will be comparatively large. p

In general the object of this invention is to provide a strong and durable construction of resistance unit of the above type, and in which the construction is adapted for use with small or large resistive conductors and for end terminals or for use as intermediate terminals. Another object is to provide a construction in which the terminals may be readily and accuratel applied in position before winding the resistive conductor on the tube, which permits the resistive conductor to be readily wound and connected to the terminals" and with the required accuracy and numberiof turns between terminals, or the proper amount of resistance between terminals. and particular features of this invention will be understood from the following de= scription and accompanying drawings,

which illustrate a preferred embodiment thereof.

Other objects and" advantages Fig. 1 is a side view of one of the completed units. Fig. 2 is an end view thereof. Fig. 3 is a side view showing the construction before application of the insulating coating. ,Fig. 4 is a similar side view of the opposite side from that shown in Fig. 3, and Fig. 5 is a development of one of the termmal or tap connections.

The insulating tube 1 is shown in this instance as carrying a series of terminals, the number being adapted for the requirements of any particular case and are firmly positioned on the tube and located in such positions as will permit the proper number of turns to be wound between adjacent terminals. In this instance, a few turns of a comparatively large braided conductor 2 are Qshown between certain of the terminals and "a. comparatively small resistive wire 3 of many turns are shown as wound betweenand connected to the other terminals.

The terminals are stamped from sheet copper preferably, and are given a contour of their parts, such as will serve the purpose of forming outside connecting portions, clamping portions for serving as convenient means for connecting the resistive conduc, tor thereto, either small or large, and also having portions for. guiding the resistive conductor as it passes to and from the terminal strip. The strip is also formed in such a manner as to insure the resistive conductor being held closely against its support and also permit the insulating coating to securely anchor the strip to the tube as well as the conductor and also cover and seal the oints.

Referring to Fig. 5 the central portion 4l' 1s of comparatively large size and forms the portion for connection to the'outside circuit. The parts l t each have a perforation ;5,.which is punched out so as to form outwardlykprojecting edges 5'. The parts 4-4 are adapted to be bent toward each other on the dotted line6 bringing the perforations 5 opposite each other for receiving the screw or bolt of the outside connection. The outwardly extending edges 5' give a firm seat against which the screw, bolt or nuts of the external connectionmay beclamped and also has the advantage that after the insulating coating is ap lied to the unit, it is only necessary. to 0 can the outer edges of the projecting parts 5' for securing a good electrical connection to the outside circuit with the terminal strip. The parts H each have similar shoulders 7 and reduced portions 8, which when the parts are bent together on the line 6 form a neck adapted to receive a reinforcing collar 9 of sheet metal shown in Figs. 3 and 4:. This collar 9 is preferably of iron or some metal having greater strength and stiffness than copper and is preferably secured in place around the neck of the terminal strip by welding the meeting ends of the collar. The collar 9 also has projecting portions extending circumferentially and over the terminal strip and in this instance are shown as two lugs 10 on each side of the collar 9. These lugs insure that the collar 9 and terminal portion of the strip will have and permanently maintain an upright position in relation to the unit.

Referring again to Fig. 5 the dotted lines 11 show the lines upon which the terminal strip isv bent at nearly right angles to the upright connection portion of the strip. The parts to the left and right of the two dotted lines 11 represent the port-ionsof the terminal strip which engage the tube 1 and form a ring thereon. Referring to the lefthand portion of Fig. 5, there is a projecting tongue 12, to which small resistive conductors are adapted to be connected. There are also projecting horns 13, 13' on opposite sides of the strip and located in such relation to the tongue 12 that the resistive conductor is readily guided to and from the tongue and also held in close contact with the tube 1 by these horns, so that the insulating coating willfully cover and securely hold the resistive conductor directly against the tube, thus avoiding any chance of the conductor workingv loose or being improperly covered with the insulating coating. The horns'13, 13 are bent outward slightly from' the tube. The arrangement of the conductor in relation to this portion of the terminal strip is well shown in the right-hand part of Fig. 3. When the terminal strip forms an outer terminal as shown at the right in Fig. 3, the tongue 12 bent outwardly from the strip, a few turns of the resistive conductor is made around the base thereof, and the tongue pressed or hammered down over the main portion of the strip as shown in Fig. 3, and the resistive conductor is then passed therefrom under the horn 13' and continues around the tube to the next terminal strip. There it is passed under the horn 13 and around the base of the tongue 12, which is then bent down to hold the conductor in intimate contact therewith and then passes under the horn 13' at the other side of the strip and thence around the tube to the next terminal strip where it is connected thereto in a similar manner.

The right-hand portion of the strip shown in Fig. 5 is adapted for connection thereto of heavy resistive conductors such as a braided wire. This portion of the strip is provided with a somewhat enlarged perforated part 14 having perforation 14:. The part around the perforation is pressed outwardly slightly to receive the head of a rivet 15 in the space between the strip and the tube, the neck of the rivet extending radially outward through the perforation 14' as shown in next to the right-hand terminal strip in Fig. 4. On one side of the strip near the part 14 is formed a horn 15 and on the opposite side of the strip is similarly formed a horn 15". These horns are not directly opposite each other but are displaced relatively to the center of the part 1 1 so as to have a position in relation thereto for guiding the conductor to or from its connection to the strip. These horns 15, 15 'are bent outwardly from the tube slightly so as to not only guide the conductor, but also hold the same in close ongagement with the surfaceof the tube as above referred to in connection with the horns 13, 13. The guiding and connecting to the strips of a braided conductor is shown in the right-hand portion of Fig. 4. The braid is divided where it engages the strip to pass on both sides around the shank of the rivet 15 as shown on next to the right hand strip of Fig. 4. A cup-shaped copper washer 16 with its shallow side toward the tube is then placed over the braid and shank of the rivet 15, the outer end of which is then reamed over the outer surface of the washer 16 to securely clamp and hold the conductor against the terminal strip. This washer is preferably larger than the circular part 14, which as before stated is pressed outwardly somewhat to receive the head of the rivet on its inner surface; and the washer 16 is sufficiently large to envelop the embossed portion 1 1 and to press the conductor closely against the portion 11 and against the insulating tube by its edges. Referring to the right-hand tenninal strip of Fig. 4c the braided conductor after being secured thereto as above stated, is passed under the horn 15 and then around the tube and under the horn 15 of the next terminal strip to which it is connected as above described, and then'passes under the horn 15, of that strip and around the tube to the next terminal strip to which it is connected in the same manner.

The outer ends 17 of the terminal strip are made narrow so that they may readily be twisted together as shown at 18 in Fig. 3, to serve as a means for holding the terminal strips in position on the tube Cur-- ing the winding and connecting of the resistive conductors. The terminal strip is also shown serrated at its edges with projections and cutaway portions, other than the parts already referred to, and as shown in Fig.- 5, for the purpose of enabling'the insulating coating 20 to attach the strip firmly to the tube. Likewise the perforations 19 in the strip near the terminal portions are also provided so that the enamel or other insulating coating may engage the tube therethrough and serve to hold the terminal strips in more intimate engagement with the insulating tube 1. Obviously the stripmay be otherwise perforated or be otherwise shaped at its edgesthan as shown in Fig. 5 for the purpose referred to. v

When the terminal strips and conductors are applied to tube 1 as shown in Figs. 3 and 4, the device is covered by the insulating coating 20 and afterwards baked or fused. The edges of the projections 5 are then cleaned for reception of the dutside terminal connections.

It is thus apparent that this invention provides a strong and durable construction and one in which the connecting strip is adapted for use with either small or large resistive conductors and also adapted for use as an end terminal connection or as an intermediate or tap connection. The' horns or projecting lugs on the .side of the strip insure that the wire-or braid will lie-closely against the insulating tube and be guided to the connecting-parts. The narrow ends of the strip provide the neans for holding the strips in place by merely twisting them together without the use of any auxiliary parts; and the irregula edges or serrations ofthe strip-and their holes placed near the neck permit the enamel or other insulating coating to engage the porcelain over a. large surface at the edges of the strip and securely anchor it in place. to the .tube. The construction'p'ermits the terminals to be placed accurately in place upon the tube before the resistive conductor is wound thereon. The strip is not only provided with a tongue or ear to which a wire may be secured and afterwards bent down, but also provides a large contact surface for a large. braided conductor,'and arranged so that the shank of a rivet .head will project radially -out-.

ward for convenience of placing portions of the braided wire on each side thereof during' winding; and a close contact is made over a comparatively large surface by means of spinning down the shank of the rivet over the cup-shaped washer, which also insures that the braid is forced against the porcelain so that the insulating coating will well cover the joint to properly seal it. The sheet iron reinforcing collar around the neck of the terminal portion-of the strip with its supporting lu s, insures strengthof the v parts so that t e tube may be heldin place 'and'supported by its terminal connections.

The outwardly projecting bosses around the holes 5 also serve to give rigidity and are terminal adapted to withstand the pressure of the bolt and nut in making a good electrical connection at the terminals. The features above referred to have served to make the device fully meet the requirements of a.

resistance tube of this character where rigid terminals are required, besides affording convenience and simplicity of manufacture.

Although I have described a particular form of my invention,,modifica-tions may be made without departing from the scope thereof.

I claim:

1. A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal encircling said support and having its ends twisted together to secure the terminal in position.-

2. A resistance unit comprising a tubular support, a conductor wound. thereon, and a terminal of sheet metal encircling said support and having a portion extending outwardly from said support for connection to an external circuit and having other portions twisted together to secure, the sheet metal terminal in position on said support.

3. A resistance unit comprising a tubular support a conductor wound thereon, and a of sheet metal having a central portion bent on itself andextending outwardly from said support for connection to an external circuit and having end portions twisted together to hold said terminal in place on said support.

4. A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal having doubled portions extending outwardly from said support for connection to an external circuit, said portions having an opening therethrough and having integral outwardly extending raised portions around said openmg. I

5. A resistance unit comprising a tubular support, a conductor woundthereon, and a terminal of sheet metal on said support having perforated central portions bent toward each other to form .outwardly extending portions for connection to an external circuit, said central portion having integral outwardly extending raised portions around a said perforations, and said terminal also collar around the inner portion thereof. 7. A resistanceunit comprising a tubular support, a conductor wound thereon, and a position on said sup: v 120 :itending portion having a reinforcing metal terminal of sheet metal secured to said support and having an outwardly extending portion doubled on itself for connection to an external circuit, and said outwardly extending portion having a reinforcing metal collar around the inner portion thereof and said collar having circumferentially extending supporting lugs.

8. A resistance unit comprising a tubular support, a conductor wound thereon, a terminal of sheet metal encircling said support, said terminal havingserrated edges where engaging said support, and an insulating coating over said conductor and terminal.

9. A resistance unit comprising a tubular support, a conductor wound thereon, a ter minal of sheet metal encircling said support, said terminal having serrated edges and interior cutaway portions where engaging said support, and an insulating coating over said conductor and terminal.

10. A resistance unit comprising a tubular support, a conductor Wound thereon, and a terminal of sheet metal having an outwardly extending portion for connection to an external circuit and a portion encircling said support for securing the terminal to said support, said encircling portion having perforations near said outwardly extending portion, and an insulating coating covering said conductor and the encircling portion of said terminal.

11. A resistanceunit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to said support, said terminal having means for securing said conductor thereto and also having a projection for guiding said conductor to said means.

- 12. A resistance unitco-mprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to said support, said terminal having means for securing said conductor thereto and also having a projection for guiding'said conductor to said means and for holding said conductor against said support.

13. resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to said support, said terminal having means for securing said conductor thereto and also having a projection for guiding saidconductor to said means and another projection for guiding said conductor from said means.

14. A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to said support, said terminal having means for securing said conductor thereto and also having a. projection for guiding said conductor to said means and another projection for guiding said conductor from said 15. A resistance unit comprising a tubular support, a conductor wound thereon, j and a terminal of sheet metal secured to and encircling said sup-port, said terminal having a projection to which conductor is secured and also having a projection for guiding said conductor to said first named projection.

16. A resistance unit comprising a tubular support, a conductor Wound thereon, and a terminal of sheet metal secured to and encircling said support, said terminal having a projection to which said conductor is secured and also having a projection for guiding said conductor to said first named projection and a third projection for guiding said conductor from said first named projection.

17 A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to and encircling said support, said terminal having a projection to which said conductor is secured and also having a projection for guiding said conductor to said first named projection and a third projection for guiding said conductor from said first named .projection, said second and third projections also holding said conductor against said sup-port. I

18: A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal secured to and encircling said support, said terminal having a portion raised from said support, and a rivet having its head under said raised portion for securing said conductor to said terminal.

19. A resistance unit comprising a tubular support, a conductor Wound thereon, and a terminal of sheet metal secured to and encircling said support, said terminal having a portion raised from said support, and a rivet having its head under said raised portion and a shank radially extending from said support, said conductor passmg over said raised portion by said shank, and

a cup shaped washer on said shank and having its edges engage said conductor.

20. A resistance unit comprising a tubular support, a conductor wound thereon, and

a terminal of sheet metal secured to and encircling said sup-port, said encircling portion of the terminal having a projection for securing a small sized conductor thereto and said encircling portion also having means for securing a large sized conductor thereto, and said encircling portion also having projections for guiding the conductor to said first named projection and to said means and for holding the conductor against said support.

21. A resistance unit comprising a tubular support, a conductor wound thereon, and a terminal of sheet metal having a portion encircling said support and having a projecting portion forconnection to an external circuit, said encircling portion having means displaced from each other whereby said conductor may be secured thereto at displaced points, and said encircling portion having ends twisted together for securing the terminal in position.

22. A resistance unit comprising a tubular support, a conductorwound thereon, and

a terminal of sheet metal having a. portion encircling said support and having a projecting portion for connection to an externalcircuit, said encircling portion having means displaced from each other whereby said conductor may be secured thereto at displaced points, and said encircling portion having projections for guiding said conductor to said means and for holding said conductor against said support. 

